Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.3.5.1 (succinate dehydrogenase)
 8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Some characteristics of a fumarate reductase from Streptococcus faecalis are described. The enzyme had a pH optimum of 7.4; optimal activity was observed when the ionic strength of the phosphate buffer was adjusted to 0.088. The K(m) value of the enzyme for reduced flavin mononucleotide was 2 x 10(-4)m as determined with a 26-fold preparation. In addition to fumarate, the enzyme reduced maleate and mesaconate. No succinate dehydrogenase activity was detected, but succinate did act as an inhibitor of the fumarate reductase activity. Other inhibitors were malonate, citraconate, and trans-, trans-muconate. Metal-chelating agents did not inhibit the enzyme. A limited inhibition by sulfhydryl-binding agents was observed, and the preparations were sensitive to air oxidation and storage. Glycine, alanine, histidine, and possibly lysine stimulated fumarate reductase activity in the cell-free extracts. However, growth in media supplemented with glycine did not enhance fumarate reductase activity. The enzymatic activity appears to be constitutive.
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PMID:Fumarate reductase activity of Streptococcus faecalis. 496 Aug 92

Electron transport and production of O2-/H2O2 by the NADH dehydrogenase flavin-semiquinone (FMNH.) and ubisemiquinone (UQH.) were studied in a model of in vivo ischemia-reperfusion in rat kidney. H2O2 production rates were assessed in isolated mitochondria using either succinate, with and without antimycin, or malate-glutamate, with and without rotenone. Respiratory activities of isolated mitochondria and activity of NADH- and succinate-cytochrome c reductase and of NADH- and succinate-dehydrogenase in submitochondrial particles were measured to evaluate the electron flux throughout respiratory carriers. The mitochondrial H2O2 production rate was approximately 1.5- and 4-times increased in ischemic and ischemic-reperfused kidneys, respectively. Ischemia caused a marked decrease in the electron transport throughout the NADH-UQ segment with no significant changes either in the NADH dehydrogenase activity or in the electron flux trough the succinate-cytochrome oxidase segment. Reperfusion did not further affect the NADH-ubiquinone segment but markedly inhibited the succinate-supported oxygen consumption, succinate-cytochrome c reductase and succinate dehydrogenase activity. Our results show a redistribution of the electron flux with an increased rate of superoxide anion/hydrogen peroxide production at NADH dehydrogenase in mitochondria subjected to ischemia only. After 10 min reperfusion an impairment of the electron flow at succinate-cytochrome c segment is established and hydrogen peroxide production by UQH. increases up to maximal values becoming the major source of superoxide anion/hydrogen peroxide.
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PMID:Mitochondrial sites of hydrogen peroxide production in reperfused rat kidney cortex. 772 10